1. Field of the Invention
The present invention concerns a steam-heated roll having a heating chamber arrangement that can be charged with steam through a feeding connection arrangement.
2. Discussion of Background Information
In the manufacture of paper and other material webs, glazing is often necessary. In this regard, the material web is fed through a roll arrangement having at least one nip or gap, in which increased pressure is exerted on the material web. Among other things, this type of treatment is utilized to improve the characteristics of the surface.
In many cases, it is necessary to apply not only increased pressure on the material web, but also increased temperature. To accomplish this, at least one of the two rolls forming the nip is heated. A broad type of heating is realized by using a roll supplied with steam that transfers its heat to the roll. In this process, the steam is fed into a heating chamber arrangement inside the roll. While excess steam is dissipated from the heating chamber arrangement, a portion of the steam condenses. Theoretically, this effect is positive because, through condensation, a maximum amount of heat is transferred to the roll. However, the condensate, e.g., water, if water steam is used, must be removed from the roll.
Steam flow is currently used for this purpose, i.e., the steam flowing through the roll is used as a "steam surge" that drives the water out of the roll. This steam surge requires a relatively high expenditure of energy and costly differential pressure control. Moreover, under working conditions with lower steam temperatures and/or pressures and high work speeds, this arrangement leads to problems with drainage of the roll because the losses in pressure within the roll are too high and the condensate must be conveyed to the center of the roll in opposition to centrifugal force. Generally, the inflow conduit and outlet pipes for the steam are guided outwardly through a centrally located connection.